JNCIS-ENT IS IS Practice Question
How does an IS-IS router identify the DIS in its hello packets?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
By the router's System ID followed by a non-zero pseudonode ID.
The DIS is identified by the System ID and a pseudonode number (the 7th byte of the LSP ID).
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
By a special flag in the header.
Why it's wrong here
There is no specific 'DIS flag' in the header.
- ✗
By the area address.
Why it's wrong here
Area address is for identification, not DIS status.
- ✗
By the MAC address only.
Why it's wrong here
MAC is for election, but the LSP ID is the identifier.
- ✓
By the router's System ID followed by a non-zero pseudonode ID.
Why this is correct
The pseudonode ID makes the DIS unique for that segment.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official Juniper Networks exam blueprint
This JNCIS-ENT practice question is part of Courseiva's free Juniper Networks certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the JNCIS-ENT exam.